Backscattering of electrons

LEED Low-energy electron diffraction [62, 75, 105] Elastic backscattering of electrons (10-200 eV) Surface structure... 

For thick substrates, backscattered electrons from the substrate decrease contrast and the minimum dimension increases to about 20 nm. For thick resists, and samples thick compared to the primary electron penetration range, electron scattering in the resist (forward scattering) and backscattering of electrons from the substrate, become more important than the electron interaction range. In these cases, exposure dose is sometimes altered according to the local pattern density to compensate for variations in the backscattered... 

Be able to exhibit sub-micron resolution (resolution being affected more by backscattering of electrons than by diffraction effects since the de Broglie wavelength of electron beams is of the order of a few tenths of an Angstrom),... 

The exact measurement of concentration needs a ZAF correction method (see p. 1097). This considers the differences in the stopping power and the backscattering of electrons between specimen and standard (Z correction), in the depth distribution of X-ray generation and absorption (A) of X rays recorded under a takeoff angle of 40-60°, and in the excitation of X-ray quanta of the element of interest by characteristic X rays and continuum of the matrix fluorescence F),... 

EXAFS Extended x-ray absorption fine structure [177, 178] Variation of x-ray absorption as a function of x-ray energy beyond an absorption edge the probability is affected by backscattering of the emitted electron from adjacent atoms Number and interatomic distance of surface atoms... 

A different form of miniature electron multiplier. The curved shape is used to reduce backscattering of the electrons. The final output of electrons flows along a wire to an amplifier. 

X-ray absorption spectroscopy combining x-ray absorption near edge fine structure (XANES) and extended x-ray absorption fine structure (EXAFS) was used to extensively characterize Pt on Cabosll catalysts. XANES Is the result of electron transitions to bound states of the absorbing atom and thereby maps the symmetry - selected empty manifold of electron states. It Is sensitive to the electronic configuration of the absorbing atom. When the photoelectron has sufficient kinetic energy to be ejected from the atom It can be backscattered by neighboring atoms. The quantum Interference of the Initial... 

In this type of Microscopy a fine beam of electrons is scanned across the surface of an opaque specimen to which a light conducting film has been applied by evaporation. Secondary electrons, backscattered elections, or (in the electron microprobe)... 

In SEM, the surface of the polymeric surface is scanned using an electron beam with the reflected or backscattered beam of electrons collected and displayed on a cathode ray tube screen. The image represents the surface contour of the scanned material. Because the surface must be conductive, most polymer surfaces must be overlaid with a conductive coating. Magnifications up to about 50,000 are carried out using SEM. 

Fig. 30. Schematic representation of the backscattered secondary-electron spectrum associated with an (isolated) external source of monoenergetic electrons of energy E. "ntis logj(E) vs. log (E) display mode emphasizes the separation of the spectrum into three parts (1) the secondary cascade which is bounded at high energies (at E p) by (2) the region of rediffused primaries which is bounded by (3) the elastic peak. At low energies the cascade is attenuated by the escape probability P(E). Auger and characteristic loss processes, among other things are not included in this idealized spectrum. (From Ref. " )...

Abstract. We compute the velocity correlation function of electronic states close to the Fermi energy, in approximants of quasicrystals. As we show the long time value of this correlation function is small. This means a small Fermi velocity, in agreement with previous band structure studies. Furthermore the correlation function is negative on a large time interval which means a phenomenon of backscattering. As shown in previous studies the backscattering can explain unusual conduction properties, observed in these alloys, such as for example the increase of conductivity with disorder. 

Figure 12 shows the more favorable case of electron beam exposure of the multilayer siloxane resist. Here, the exposure due to backscattered electrons is reduced from 86% to 50% of the primary exposure, and the imaging layer is very thin. Exposure in the 1 x 1 aperture exceeds 70% and is... 

Figure 6.17 shows a schematic of the LEED system. The sample is bombarded through the left by a beam of electrons. Only radiation or electrons (remember the wave nature of matter ) with the same energy as the incident beam are detected. These electrons are called elastic backscattered electrons. The detection system is a fluorescent screen placed in front of the sample. Holding the screen at a large positive potential accelerates the electrons. Once they reach it, they excite the phosphorus in the screen, marking it with bright spots characteristic of the diffraction pattern. Finally, a camera in front of the screen records the diffraction pattern. 

The oxidation of iron at temperatures between 500 and 700 K was also studied by means of backscattered conversion electron spectroscopy by Simmons et al. (235). An example of these typical upside-down backscatter spectra is shown in Fig. 36. The authors found that the kinetics for oxide formation followed a parabolic rate law and that the resulting oxide formed at these low temperatures was nonstoichiometric Fe304. 

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